The present invention relates, in general, to an apparatus for improving the ultrasonic bonding of electrical connections to an electrical component, and more particularly, to a heated tool useful for tape automated bonding of integrated circuits.
Bonding of this type is typically accomplished by a combination of heat and ultrasonic energy applied to the bond site while a lead and associated pad are held together by means of a specially designed bonding tool.
In the past ultrasonic energy was applied through the bonding tool while the heat was applied by heating the pedestal which holds the electrical component in position. This method has the inherent disadvantage that the component must be heated to a higher temperature than the bond site. Components having several hundred electrical connections require large packages which act as effective heat sinks, so the component must be heated to an unacceptably high temperature in order to obtain an adequate temperature in the area being bonded.
A solution to this problem has been to heat the bonding tool itself either by means of a heater cartridge mounted inside the transducer horn assembly or by wrapping a heater directly around the bonding tool itself. These approaches have the disadvantage that they interfere with the finely tuned ultrasonic characteristics of the bonding tool and transducer horn assembly, thus compromising the efficiency of the ultrasonic energy transfer.
Accordingly, it would be desirable to overcome these deficiencies by heating the bonding tool without making physical contact to ultrasonically excited components.